This invention relates to flame-retardant polyester filaments suitable for use in textile fabrics, and is more particularly concerned with a continuous process for producing them.
Serious difficulties have been encountered in preparing flame-retardant polyester filaments for use in textile fabrics. The flame-retardant compound must not adversely affect the whiteness, hand and strength; it must have the proper combination of melt stability, melting point, low volatility, photostability and low toxicity; and it must impart an adequate flame retardancy which is durable against removal in fabric finishing and use.
Halogenated compounds have been used in synthetic polymers to impart flame retardant properties. One such compound which has been suggested for the production of copolyester fibers having improved flame retardance is 2,2-bis-[4-(2-hydroxyethoxy)-3,5-dibromophenyl] propane. This compound (designated herein as HDP) is represented by the structural formula ##SPC1##
Since HDP is a glycol, it can be copolymerized with the polyester to avoid difficulties with removal encountered with melt additives.